/Engine/Plugins/Experimental/MeshLODToolset/Source/MeshLODToolset/Public/Graphs/GenerateStaticMeshLODProcess.h
the converted source MeshDescription as a FDynamicMesh3, valid afterInitialize()finishes
const [FDynamicMesh3](API\Runtime\GeometryCore\DynamicMesh\FDynamicMesh3) & GetSourceMesh() const